Check what kind of account you have. It might happened that it changed your user group from administrator to user. Which is very reasonable. Also check your account properties.
In DOS, there is only one user which is Administrator as DOS is a single user Operating System.. When we talk of DOS shell integrated with Windows, the Windows Administrator is then also the DOS Administrator..
By default, there is no password set for the hidden administrator account on Windows XP. When setting up this account and enabling it, the user must create their own password.
The computer administrator determines what the Firewall properties will be. The firewall is accessed through the control panel.
Create a Windows XP forgotten password floppy disk
As administrator, you can create unique 'user accounts'.
The administrator of the Windows XP can set up new accounts or deny users from setting up accounts.
I would suggest installing windows on one hard drive, then installing ubuntu on the same hard drive. Use the other hard drive for the backups (partition it).
Create a restore point.
The account you used to delete the administrator acount must have admin rights. Use that account to create an account with administrator rights called Administrator. control panel -> user accounts -> add or remove accounts -> create new account
If you mean user then: You must have administrator rights. For windows: Start Menu >> Control Panel >> Users >> Create new User For Mac: Apple Icon >> System Preferences >> Users >> Create new User
Control panel -> User accounts. Depending on your Windows version you might have to click "Manage another account" before given the possibility to "Create new account". Choose "Administrator" in the setup wizard.
For doing this simply, select full clean install while Installing 7. This will enable you to first format your drives, create new partitions if you wish to and have a freshly installed Windows 7. Further, if you upgrade from Vista keeping your files and docs intact, the old Windows' folder will be replaced by new one. So you cannot then delete it.